The present invention relates generally to a hermetic compressor assembly and, more particularly, to a direct suction compressor assembly having a crankcase mounted within a hermetically sealed housing. Suction gas is delivered directly to the crankcase, or a cylinder head attached to the crankcase, from a refrigerant system suction line outside the housing by means of a suction inlet connector or adaptor. In general, prior art hermetic compressor assemblies comprise a hermetically sealed housing having a compressor mechanism mounted therein. The compressor mechanism includes a crankcase or cylinder block having a cylinder/compression chamber formed therein for compressing and discharging gaseous refrigerant.
In a high side reciprocating compressor, which is characterized by a pressurized housing, suction gas received from a refrigeration system is introduced directly into the compression chamber, or at least a suction cavity adjacent the compression chamber. This is generally accomplished by means of a conduit extending from outside the housing to the compression chamber within the crankcase. This configuration is commonly referred to as a direct suction compressor assembly. In direct suction compressor assemblies, a suction inlet conduit is introduced through the hermetically sealed housing, through a discharge chamber formed in the housing, and into a suction inlet bore formed in the crankcase/cylinder block or cylinder head. The suction inlet bore is directly or indirectly, such as through a suction cavity formed in the cylinder head, in communication with the compression chamber. That portion of the tubing external to the housing may comprise part of a suction accumulator or may constitute a fitting to which a suction line of a refrigeration system is attached.
One problem associated with assembly of direct suction type compressors concerns misalignment of the suction inlet bore of the crankcase with respect to the suction inlet opening and inlet fitting in the housing sidewall and the suction conduit therebetween. Misalignment can lead to excessive stress and material degradation with respect to the suction conduit and related coupling devices. Manufacturing tolerances for component parts of the direct suction compressor assembly, i.e., parts having apertures and openings through which the suction conduit extends, may complicate compressor assembly and result in undesirable stress on the suction conduit once the compressor is assembled.
A second problem associated with the above-characterized direct suction compressor assembly occurs during compressor operation and relates to the transmission of vibration and noise from the compressor assembly to the housing by means of the suction conduit and associated linkages therebetween. Specifically, the compressor mechanism may undergo slight excursions in response to axial, radial, and torsional forces acting thereupon during compressor operation. Consequently, the nature of the linkage between the compressor mechanism and the stationary housing determines the extent to which vibration and noise are imparted to the housing.
The suction inlet connector must also withstand such forces and maintain seal integrity to prevent leakage from the interior of the housing. One common prior art approach to compensating for radial spacing and movement between the housing and the crankcase suction inlet opening is the provision of an O-ring seal within the suction inlet bore and/or the suction inlet fitting to allow the suction conduit to variably penetrate into the bore. Typically, this approach utilizes a fitting at the housing opening which is welded to the housing and brazed to the conduit. A primary problem of this arrangement is that it provides for only one degree of freedom for movement of the compressor during operation, radial movement.
Another prior art approach to compensating for misalignment involves a suction tube connector directed to compensating for spacing variations between the housing and the compressor crankcase. A tube is disposed radially inwardly from the housing sidewall and is provided with a slotted conical flange at one end to abut against the crankcase in the general area of the suction inlet bore. The divergent end of the conical flange has a diameter greater than the suction inlet bore, thereby permitting alignment variations.
With respect to suction line connectors for use in indirect suction hermetically sealed compressor assemblies, i.e., low side compressors where the suction gas enters into the interior space of the housing, a suction line adapter device is known which is attached to the housing as by welding. This adapter comprises two pieces, one of which is welded to the housing at the location of the opening therethrough and the other being a coupling member attachable to a refrigeration system suction line as by brazing or the like. The coupling member with suction line attached thereto is then screwed onto the fitting welded to the housing for sealing engagement therewith. A nut threadably engages each of the two components and brings them forcibly together at a surface to surface juncture having an O-ring seal seated there between.
Further, a suction line adaptor is known which comprises a pair of L-fittings respectively attached to the housing and the crankcase at axially spaced locations thereon, and a connecting pipe inside the housing between the pair of L-fittings axially perpendicular to and disposed between the housing and the crankcase. The connecting pipe is capable of moving relative to one or both of the L-fittings to compensate for variations in radial and axial spacing between the housing and the crankcase. A problem with such a suction tube adapter is that space is required between the crankcase and the housing sidewall within the housing. Also, this type of adaptor complicates assembly and is not suitable for high side compressor applications.
Prior suction inlet adapters and couplings for use in direct suction type hermetic compressors are disclosed in U.S. Pat. No. 4,844,705 (Ganaway) and U.S. Pat. No. 4,969,804 (Ganaway), which are hereby incorporated into this document by reference and which are assigned to the assignee of the present invention. U.S. Pat. No. 4,844,705 discloses a suction line adapter which includes a tubular insert disposed between the suction inlet bore of the crankcase and the suction inlet opening formed in the housing sidewall. The tubular insert is sealed with respect to the suction inlet bore of the crankcase by use of an O-ring. The tubular insert is sealed with respect to the suction inlet opening of the housing by use of an outwardly extending flange disposed between three component parts of a suction inlet adapter coupling. U.S. Pat. No. 4,969,804 discloses a tubular insert which is sealed at one end to the suction inlet bore of the crankcase by use of an O-ring. The tubular insert is sealed at the opposite end with respect to the suction inlet opening in the housing by use of an O-ring and a three-piece suction adapter coupling.
Typically during compressor operation, discharge gas is discharged from the compression chamber directly into the discharge chamber within the housing and surrounding the motor and compressor mechanism. Because the discharge gas is at a higher temperature relative to the suction gas temperature and because the motor operating efficiency decreases as the motor temperature increases due to heat absorbed from the surrounding discharge gas, the overall compressor efficiency is adversely affected.
The vortex tube effect, known also as the Ranque Vortex Tube effect, the Hilsch Tube effect, the Ranque-Hilsch Tube effect, the Coanda effect, and Maxwell""s Demon, was discovered in 1928 by George Ranque, and involves providing a dual output flow arrangement consisting of a warmer fluid flow path and a cooler fluid flow path from a single or combined fluid source. The vortex tube effect is accomplished in one respect by introducing a compressed fluid source into a vortex tube which is adapted to impart a spinning motion on the fluid flowing therethrough. The vortex tube effects the formation of an outer flow path, which flows in one direction, and an inner flow path, which flows in an opposite direction. This effect is characterized in that the inner flow path gives off kinetic energy in the form of heat to the outer flow path, whereby an output of cooler fluid occurs at one end of the vortex tube and an output of warmer fluid occurs at an opposite end of the vortex tube.
The present invention involves establishing bidirectional flow paths of discharge gas in a discharge plenum for cooling the motor during compressor operation. The present invention provides a discharge gas passage and surrounding the lower portions of the stator and rotor and in communication with a gas compression chamber within the compressor mechanism. During compressor operation, discharge gas is forcibly expelled from the gas compression chamber through a discharge passage, and into the discharge plenum.
According to the present invention, the spinning motion of the rotor imparts a spinning vortex effect on the discharge gas collected in the discharge plenum. The vortex effect causes an inner flow path and an outer flow path to form. The inner flow path flows in a direction opposite the outer flow path and gives off kinetic energy in the form of heat to the outer flow path. A first gap is provided between the rotor and the stator and a second gap is provided between the casing and the stator. The cooler or reduced temperature fluid in the inner flow path flows from the discharge plenum through the first gap and is discharged into the discharge chamber formed in the compressor housing. The warmer or elevated temperature discharge gas in the outer flow path travels through the second gap and is discharged into the discharge gas chamber. By circulating cooler fluid between the rotor and the stator, the motor is effectively cooled, resulting in enhanced motor operating efficiency and increased overall compressor operating efficiency. This is in dramatic contrast to direct suction hermetic compressors of the prior art in which discharge gas is discharged generally directly into the discharge chamber of the housing after compression.
Yet another advantage of the present invention is that discharge gas collected in the discharge plenum is subjected to the vortex tube effect during compressor operation, thereby effecting a continuous flow of cooler fluid through a gap formed between the rotor and the stator. The flow of cooler fluid effectively cools the motor during compressor operation and increases motor operating efficiency and overall compressor operating efficiency.
In another embodiment, the present invention provides a reciprocating hermetic refrigerant compressor having a hermetically sealed housing, a compressor mechanism, and a motor. The housing provides a sidewall having a suction inlet opening. The compressor mechanism is disposed in the housing and has a suction inlet bore, a gas compression chamber and a discharge passage formed therein, the discharge passage in communication with a discharge plenum.
The motor includes a stator attached to a crankcase, and a rotor attached to a crankshaft drivingly connected to the compressor mechanism and surrounded by the stator. A first gap is formed between the rotor and the stator and a second gap is formed between the stator and the crankcase. During compressor operation discharge gas travels through the discharge cavity, through the discharge passage, and through the first and second gaps. The rotor spins during compressor operation resulting in the Ranque vortex tube or Coanda effect, which accomplishes enhanced cooling of the motor.
In a further embodiment, the present invention provides a method of cooling a motor in a hermetic refrigerant compressor. The compressor includes a compressor mechanism having a gas compression chamber therein, such as a crankcase with a cylinder, and a motor having a stator and rotor. The method comprises the following steps. Gas is discharged from the gas compression space during compressor operation into a discharge gas plenum provided in the compressor crankcase. A spinning vortex of discharge gas is generated within the discharge plenum, whereby an inner flow path of cooler gas and an outer flow path of warmer gas are formed. A first gap between the stator and rotor and a second gap between the stator and crankcase are formed in the compressor. The cooler gas in the inner flow path travels through the first gap and the warmer gas in the outer flow path travels through the second gap.
Accordingly, the present invention provides a hermetic refrigerant compressor including a hermetically sealed housing having a wall with a suction opening, a compressor mechanism disposed in the housing and having a gas compression chamber therein and a discharge passage in communication with a discharge plenum, and a motor including a stator and a rotor attached to a crankshaft drivingly linked to the compressor mechanism. The rotor is surrounded by the stator and a first gap is formed between the rotor and stator. A second gap is formed between the stator and the compressor mechanism. During compressor operation discharge gas expelled from the gas compression chamber travels through the discharge passage, through the discharge plenum, and then through the first and second gaps. The rotor spinning during compressor operation causing a spinning vortex of refrigerant gas to occur in the discharge plenum, the vortex having an outer flow path of warmer gas and an inner flow path of cooler gas. The outer flow path of warmer gas generally travels through the second gap and the inner flow path of cooler gas generally travels through the first gap for enhanced motor cooling.
The present invention also provides a hermetic refrigerant compressor including a hermetically sealed housing having a wall with a suction opening, a compressor mechanism disposed in the housing and having a gas compression chamber therein and a discharge passage in communication with a discharge plenum, and a motor including a stator and a rotor attached to a crankshaft drivingly linked to the compressor mechanism. The rotor is surrounded by the stator, and a first gap is formed between the rotor and the stator. A second gap is formed between the stator and the compressor mechanism. During compressor operation discharge gas expelled from the gas compression chamber travels through the discharge passage, through the discharge plenum, and then through the first and second gaps. The rotor spinning during compressor operation forms a first flow path of warmer gas and a second flow path of cooler gas. The first flow path of warmer gas generally travels through the second gap and the second flow path of cooler gas generally travels through the first gap for enhanced motor cooling.
The present invention further provides a method of cooling the motor in a hermetic refrigerant compressor including a compressor mechanism having a gas compression chamber therein, and a motor having a stator and a rotor. The inventive methods includes communicating gas discharged from the gas compression chamber during compressor operation into a discharge gas plenum provided between the compressor mechanism and the motor; creating a spinning vortex of discharge gas within the discharge plenum, whereby an inner flow path of cooler gas and an outer flow path of warmer gas are formed; and providing a first gap between the stator and rotor and a second gap between the stator and compressor mechanism and causing the cooler gas in the inner flow path to flow through the first gap and the warmer gas in the outer flow path to flow through the second gap.